Apparatuses for continuously processing photographic film usually involves large quantities of liquid that has considerable thermal inertia and required relatively large and cumbersome apparatus. These apparatus are inconvenient and require an expensive amount of liquid to operate.
Most equipment available for lower volume processing requirements consists of one of the three following types:
1. Hand processing tank which will process film, mounted on a stainless steel reel, as long as there is latitude in the processing temperature requirements. Otherwise, the tank must be placed in a water jacket or bath, to assure proper temperature control.
2. A water jacket type tank consists of a large tank in which a series of small tanks is suspended. The large tank is filled with water either flowing at a constant temperature or tempered by an immersion heater. The film is mounted on reels suspended in the small tanks to be processed. This device allows for great accuracy in temperature control and very consistent results. The drawbacks are considerable because this unit needs constant running water, a large work area, and a heavy duty support.
3. Single drum (or rotating tank) type processing is possible for small quantities of film. However contamination and wet equipment become a problem when single drum type equipment is used for continuous processing.
4. The continuous processor is a large unit which transports the film through by the use of rollers or a web. This unit consists of an immersion heater mounted in each tank, a pump on the bottom of each tank (for circulating the processing solution), and a series of rollers used to transport the film through the tanks.
Many small professional photographers process film by hand due to the lack of fast and reliable processing equipment to meet their needs.